Field of the Invention
The present invention relates to an electrophotographic photoreceptor to be used in an electrophotographic image forming process, an image forming apparatus including the same, and an image forming method using the same.
Description of the Related Art
The electrophotographic photoreceptor (hereinafter, also simply referred to as the “photoreceptor”) constituting an electrophotographic image forming apparatus such as a copying machine or a printer is required to have a long lifespan and image quality stability of the image to be formed. In the photoreceptor, the lifespan of the photoreceptor is determined depending on the wear of the photoreceptor surface.
In recent years, as a photoreceptor which exhibits excellent durability such as wear resistance and scratch resistance and achieves a long lifespan, a photoreceptor has been developed in which a photosensitive layer is laminated on a conductive support and a surface layer in which metal oxide fine particles to which a reactive organic group is bonded are bonded to a cured product of a polymerizable monomer via a bonding group by the reactive organic group is laminated on the photosensitive layer (JP 2010-107962 A).
However, the metal oxide fine particles exhibit low conductivity since an organic substance (bonding group by the reactive organic group) is present on the surface thereof, and a problem that the memory resistance of the surface layer decreases as the cancellation of the residual potential after exposure is hindered and image memories are generated is thus caused when such metal oxide fine particles are introduced into the surface layer.
In order to solve such a problem of the memory resistance, a method to contain a charge transport material in the surface layer is known, but another problem that the durability decreases since the charge transport material acts as a plasticizer in the surface layer is caused although a certain effect of improving the memory resistance is obtained in such a photoreceptor.
In order to achieve both durability and memory resistance, a method to obtain memory resistance while securing high durability by using p-type semiconductor fine particles as a charge transport material has been proposed (JP 2013-130603 A).
Meanwhile, it is considered that it is required to further increase the speed of an image forming apparatus in the future, but it cannot be said that sufficient memory resistance is achieved even if a photoreceptor having a surface layer using the p-type semiconductor fine particles is mounted on such a high-speed machine, and also a new quality defect called fogging is caused when the amount of p-type semiconductor fine particles is increased in order to improve memory resistance.
As described above, it is extremely difficult for a photoreceptor to be mounted on a high-speed image forming apparatus to achieve both high durability and excellent memory resistance.